Pump for paper pulp



Oct. 15, 1957 o. IMSET PUMP FOR PAPER PULP Filed Nov. 24, 1953 Mae/r United States Patent 2,809,591 Patented Oct. 15, 1957 fire PUMP FQR PAPER PULP Otto lmset, Bestun, Oslo, Norway Application November 24, 1953, Serial No. 394,189

Claims priority, application Sweden November 26, 1952 9 Claims. (Cl. 103-103) The present invention relates to a pump for paper pulp comprising a housing with axial inlet and tangential outlet for pulp, and of a rotor rotatively journalled in the housing and fitted with vanes.

The invention aims particularly at providing a pump which is well adapted for the pumping of paper pulp of high consistency, so-called thick pulp. It is in general far more dilficult to pump thick pulp than, for instance, to pump water. If the thick pulp contains foreign bodies, the position is still worse. Among the impurities which cause the greatest inconvenience are textile fabrics, as these cling to the vanes and block the openings.

To separate out the foreign bodies, use in generally made of strainers. There exist also dissolvers for old paper which are provided with straining plates at the bottom, but as these strainers have perforations of 1A to l" diameter it will be realized that the pulp fractionated by these strainers cannot be satisfactorily cleaned. It is also the general experience that the pumps for this pulp must be designed for facile and frequent cleaning of the Vane heel. They allow small pieces of iron or other metals, vhich might damage the subsequent grinding unit, to slip through. This always applies when it relates to the transport of paper pulp dissolved from old paper, but it may also happen that foreign bodies get into the pulp which has been dissolved from cellulose etc., and these pass through the pump and reach the grinding units.

These foreign bodies may be, for instance, paper clips, textile fabrics, cork, iron, metals, waste rubber, matches, bits of wood etc. The need for getting rid of these foreign bodies dominates the equipment where waste paper is used as raw material.

One of the main purposes of the invention is to providepurpose is to provide a pump which does not get clogged up during use. Yet another purpose is to provide a pump which can be used for the washing of the rubbish, for the sake of the valuable and useful fibres it may contain.

What in the first place is characteristic of the pump according to the invention is that the rotor on the inlet side is fitted with a disc which covers practically the whole of the inlet opening, and that along the circumference it is provided with a large number of narrow slots, through which the pulp can pass, whereas foreign bodies will be caught by the tongues between the slots.

During this process the slots act as a self-cleaning strainer, as the foreign bodies which do not pass through the slots will by the action of the centrifugal force be led out along the tongues in a radial direction.

To obtain an effective sorting of the foreign bodies and to prevent them from passing through the slots or adhering to the edge of the inlet opening, the tongues should conveniently end in a plane which approximately coincides with the plane through the surrounding edge of the inlet opening or lies on the inlet side of this plane.

Further features and advantages of the invention will appear from the following description, in conjunction with the drawing, which depicts in schematic form and embodiment of a pump pursuant to the invention.

In the drawing Figure 1 shows anaxial section through the pump, while Figure 2 is a broken outline of the rotor or pump wheel.

In the drawing 1 denotes the pump housing, which has the form of a flat cyndrical box, which along its circumference is welded on to a flange 2 for attachment of a circular shaped plane disc 3. The inner edge 4 of the disc 3 bounds the axial inlet opening to the pump housing. 5 is the tangential outlet.

6 is a shaft journalled in the usual way for the rotor, which is executed with a relatively large number of vanes 7. The characteristic feature of the pump according to the invention is in the first place that on the front of the vanes there is a disc 8, which covers practically the whole of the inlet aperture, and along the circumference is fitted with a large number of narrow slots 9, through which the pulp can pass, while foreign bodies Will be trapped by the tongues 16 between the slots.

in the embodiment shown in the drawing the disc 8 is, as will be seen, countersunk relatively to the inlet opening, and along the periphery executed with a raised edge, in which the slots are arranged. This edge, which is formed by the tongues 10, can, for example, form an angle of 45 with the plane of the disc.

11 is a number of vanes on the front of the disc. These vanes serve to conduct the pulp outwards to the periphery of the disc. The rotor can thereby turn a great speed, while the pulp in front of the disc need only have a relatively small speed, and then mainly in radial direction. Thus a great difference in velocity is obtained between the pulp and the rotor in tangential direction, and this has the effect that it is very difiicult for foreign bodies to force their way into and through the openings.

Along the edge or" the inlet opening one or more peripherally running knives or ribs are conveniently arranged, of which one 12 is shown in the drawing, on the front of the disc 3, and another 13 on the rear of the disc. These knives have preferably an increasing thickness in the direction of rotation, e. g. from 0 to 10 mm. One of the purposes of these knives is to loosen the textile threads etc., which may possibly hang over the edge 4. Such threads will be drawn round and be carried over the knives 12 and 13, and thereby be drawn in axial direction, so that they loosen and are carried in radial direction.

in the same way as the pump, pursuant to the invention, will separate out foreign bodies, it will of course also separate out undissolved lumps of pulp. It can therefore also be used for the removal of completely dissolved pulp from a dissolver, while the undissolved pulp is retained.

The pump according to the invention can of course also be used for the pumping of pulp of lower consistency and for the pumping of pure pulp, as it may also have significanoe in this case to prevent foreign bodies from entering the pump housing. For despite all caution it happens sometimes that bolts, tools etc. are introduced into the pulp.

I claim:

1. A pump for pumping paper pulp comprising a housing having a peripheral edge defining an axial inlet and a tangential outlet, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire inlet opening, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slots for letting the pulp paper through the disc, said tongues extending to said peripheral edge on said casing, the faces of said tongues on the inlet side of said disc and the surface of said peripheral edge facing in the direction of the inlet surface of said disc being at an angle such that material too coarse to pass between said tongues may move unobstructed in a radial outward direction beyond the ends of saidtongues under the effect of centrifugal force.

2. A pump for pumping paper pulp comprising a housing having a peripheral edge defining an axial inlet and a tangential outlet, 9. pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire inlet opening, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slots for letting the pulp pass through the disc, said tongues extending to said periphera edge on said casing, the faces of said tongues on the inlet side of said disc and the surface of said peripheral edge facing in the direction of the inlet surface of said disc approximately coinciding whereby material too coarse to pass between said tongues may move unobstructed ina radial outward direction beyond the ends of said tongues under the eflect of'centrifugal force.

3. A pump for pumping paper pulp comprising a housing having a peripheral edge defining an axial inlet and a tangential outlet, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire inlet opening, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slots for letting the pulp pass through the disc, said tongues extending to said peripheral edge on said casing, the faces of said tongues on the inlet side of said disc and the surface of said peripheral edge facing in the direction of the inlet surface of said disc forming 7 an obtuse angle, whereby material too coarse to pass between said tongues may move unobstructed in a radial outward direction beyond the ends of said tongues under the efiect of centrifugal force.

4. A pump for pumping paper pulp comprising a housing having a radially inwardly directed flange, the inner edge of which defines an axial inlet, and having a tangential outlet, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire inlet opening and being spaced in the axial direction of said impeller inwardly in the pump housing from said flange, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slots for letting the pulp pass through the disc, said tongues extending at an angle to the plane of said disc to the inner edge of said flange and terminating in the plane of the surface of said flange which faces the inlet direction of said pump, whereby material too coarse to pass between said tongues may move unobstructed in a radial outward direction beyond the ends of said tongues under the effect of centrifugal force.

5. A pump for pumping paper pulp comprising a housing having a radially inwardly directed flange, the inner edge of which defines an axial inlet, and having a tangential outlet, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire inlet opening and being spaced in the axial direction of said impeller inwardly in the pump housing from said flange, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slotstfor i 4 letting the pulp pass through the disc, said tongues extending at an angle to the plane of said disc to the inner edge of said flange and terminating in the plane of the surface of said flange which faces the inlet direction of said pump, whereby material too coarse to pass between said tongues may move unobstructed in a radial outward direction beyond the ends of said tongues under the effect of centrifugal force and vanes on the inlet side of said disc for driving the pulp outward in a radial direction.

6. A pump for pumping paper pulp comprising a housing having a radially inwardly directed flange, the inner' edge of which defines an axial inlet, and having a tangential outlet, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc covering substantially the entire. inlet opening and being spaced in the axial'direction of said impeller inwardly in the pump housing from said flange, a plurality of radially outwardly extending and circumferentially spaced tongues on the periphery of said disc defining between them a plurality of narrow slots for letting the pulp pass through the disc, said tongues extending at an angle to the plane of said disc to the inner edge of said flange and terminating in the plane of the surface of said flange which faces the inlet direction of said pump, whereby material too coarse to pass between said tongues may move unobstructed in a radial outward direction beyond the ends of said tongues under the effect of centrifugal force and knives on said flange along the edge of the inlet opening.

7. A pump as claimed in claim 6 in which said knives are attached to the face of said flange facing in the inlet direction and on the face of the flange facing in the outlet direction.

8. A pump as claimed in claim 7 in which said knives increase in thickness in the direction of rotation of said impeller.

9. A pump for pumping paper pulp comprising a flat cylindrical housing open at the inlet side and having a tangential outlet, a circular plane and wall secured to the edge of said housing on the inlet side, said wall having a concentric circular opening therein defining an inlet to said housing, a pump impeller rotatably mounted in said housing, a disc attached to said pump impeller on the inlet side of said impeller, said disc being substantially the same size as said circular opening in said end wall and being spaced axially inwardly of said wall, and a large plurality of outwardly extending peripherally spaced tongues on the periphery of said disc defining between them narrow slots to let the pulp pass therethrough, said tongues extending at an angle to the plane of said disc to the edge of the circular opening in said end wall and terminating in a plane coincident with the surface of said end wall facing the inlet direction of the opening therein, the surfaces of said tongues lying wholly within the plane of rotation of said tongues, whereby foreign bodies are retained by the tongues and guided outwardly in a radially direction under the influence of centrifugal force.

References Cited in the file of this patent UNITED STATES PATENTS 

